# Which Of The Following Electron Configurations Correspond To An Excited State

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Which of the following electron configurations correspond to an excited state? Identify the atoms, and write the ground-state electron configuration where appropriate.
1s ^ { 2 } 2 s ^ { 2 } 3 p ^ { 1 }1s^22s^23p^1

Answer: The atom is Boron(B) which ground-state electron configuration is 1s^22s^22p^1

## Explanation

Electron configuration helps us see how electrons are arranged in atomic orbitals for a\nspecific element. There are four types of sub-shells s, p, d, and f. The s subs-hell has one orbital that can hold up to two electrons. The p sub-shell has three orbitals that can hold up to six electrons. The d sub-shell has five orbitals that can hold up to 10 electrons and the f subs-hell has seven orbitals that can hold up to fourteen electrons. The periodic table has all four types of sub-shells on it we refer to it as a block.

The 1A and 2A are our s block and helium is also part of the s block. The 3A,4A,5A,6A,7A, and 8A groups are representing the p block (the only exception is helium from the 8A group which is representing the s block). The inner transition metals are our d block and lanthanides and actinides are representing the f block.

We also have the specific order that we follow for finding the expected electron configuration and it is:

An element can have an expected electron configuration when we are filling orbitals in a specific order with an element’s electrons. The electrons with the same sping are always the first one to fill the orbital and after them, the electrons of opposite spin are the ones to fill an orbital. In most cases, the expected electron configuration is the same as the actual electron configuration. There is some specific example of elements in which the expected electron configuration are not the same as the actual electron configuration. This is happening because there the full-filled orbitals are more stable than half-filled orbitals and the half-filled orbitals are more stable than partially filled orbitals. So the electrons in these elements will try to fully fill some orbital or will try to half fill the specific orbital and will ignore the specific electron configuration order. We also have a condensed electron configuration that can be written with noble gas that is in the row before the element we are looking for.

(A)

1s^22s^23p^1 represents an excited electron configuration. That is because 1s^22s^23p^1 does not follow the specific order of electron configuration. We can see that 3p sub-shell cant be next to 2s sub-shell in the specific order of electron configuration. So this is an exciting electron configuration. The ground-state electron configuration for this example will be:

In the introduction, we said everything about shells and the rule of filling up the orbitals so in the 2p sub-shell we have one unpaired electron. This ground-state electron configuration has 5 electrons so it is Boron(B) electron configuration.